Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and various other medical conditions. Implantable neurological stimulation systems generally have an implantable pulse generator and one or more leads that deliver electrical pulses to neurological tissue or muscle tissue. For example, several neurological stimulation systems for spinal cord stimulation (SCS) have cylindrical leads that include a lead body with a circular cross-sectional shape and multiple conductive rings spaced apart from each other at the distal end of the lead body. The conductive rings operate as individual electrodes or contacts and the SCS leads are typically implanted either surgically or percutaneously through a large needle inserted into the epidural space, often with the assistance of a stylet.
Once implanted, the pulse generator applies electrical pulses to the electrodes, which in turn modify the function of the patient's nervous system, such as by altering the patient's responsiveness to sensory stimuli and/or altering the patient's motor-circuit output. During pain treatment, the pulse generator applies electrical pulses to the electrodes, which in turn can generate sensations that mask or otherwise alter the patient's sensation of pain. For example, in many cases, patients report a tingling or paresthesia that is perceived as more pleasant and/or less uncomfortable than the underlying pain sensation. In other cases, the patients can report pain relief without paresthesia or other sensations.
In any of the foregoing systems, it is important for the practitioner to accurately position and anchor the leads in order to provide effective therapy. Existing lead anchors can negatively impact lead performance and/or reliability when they allow the lead body to slide or otherwise change position. The movement of the lead body relative to the lead anchor can reduce the accuracy with which the stimulation is provided, thus limiting the effectiveness of the therapy. In some cases, the leads must be securely fixed but still repositionable if the practitioner determines that a different position would provide more effective therapy. Reliable retention of the leads or other signal delivery elements in the pulse generator, lead extension components, as well as components that may releasably couple a lead or other signal delivery element to an external stimulator (such as those disclosed in co-pending U.S. Patent Application Publication No. 2011/0071593 to Parker et al., which is hereby incorporated by reference in its entirety) is also important in such systems. As a result, there exists a need for a lead retention mechanism, such as a lead anchor, etc, that mitigates lead movement while providing the ability to subsequently reposition the lead.